Fuel delivery systems

Abstract

A fuel delivery system employs an evaporation chamber which preheats the fuel by means of exhaust gases prior to injection of the fuel into a carburetor. A solenoid valve operates to control the amount of fuel introduced into the evaporation chamber and the valve is controlled in operation by means of a selector circuit which controls the operation of the valve and hence, the flow of fuel according to the speed of the engine, the pollutant content of the exhaust gases, and the temperature at which the engine is operating at.

I claim: 
     
       1. A fuel delivery system apparatus for use with an internal combustion engine, the combination therewith comprising: (a) a fuel evaporator comprising a hollow chamber having an inlet port for receiving a liquid fuel, and an outlet port communicating with said inlet port, said hollow chamber surrounded by an outer heat chamber with a plurality of heat conducting fins coupled about said inner chamber and located in said heat chamber, said heat chamber having an inlet port for receiving hot exhaust fumes from said engine and an outlet port for discharging said fumes, with said fumes operative to heat said fins and therefore said hollow chamber and any liquid fuel contained therein,   (b) temperature sensing means coupled to said outer heat chamber to monitor the temperature of operation of the evaporator,   (c) exhaust gas sensing means coupled to one of said ports of said heat chamber to monitor the pollutant content of said exhaust fumes,   (d) fuel supply means having an input conduit coupled to said inlet port of said hollow chamber for introducing fuel thereto,   (e) selective valve means located between said conduit and said inlet port and operative in a first position to allow fuel into said chamber and in a second position to restrain flow,   (f) speed detecting means coupled to said engine, said speed detecting means including a rotatable shaft coupled to said engine, said shaft having a cam projection on a surface thereof, a plurality of switches positioned about said shaft and operated by said cam projection during rotation of said shaft to provide a plurality of pulses at an output during each revolution of said shaft, said pulses indicative of a first control signal manifesting the speed of said engine, with the number of said pulses during each revolution always equal and independent of the speed of said engine,   (g) a first monitoring means responsive to said first control signal and coupled to said temperature sensing means to provide a first series of output pulses each of a given initial duration during engine start-up greater than that of said pulses indicative of said first control signal, with the duration of said pulses varying according to the temperature of said evaporator,   (h) a second monitoring means responsive to said first control signal, and coupled to said exhaust gas sensing means to provide a second series of output pulses each of a duration determined by said exhaust gas content, with an initial duration during engine start-up selected to be less than that duration of said pulses of said first monitoring means,   (i) means for combining said first and second pulse trains, to provide an output signal indicative of the wider of the two pulses during engine operation,   (j) means for coupling said output signal of said combining means to said selective valve means to control fuel flow in said chamber according to said output signal, whereby fuel entering said chamber via said inlet port is preheated by said chamber in an amount according to said operation of said selective valve means to provide preheated fuel at said outlet port for applying the same to the carbureator of said engine.   
     
     
       2. The apparatus according to claim 1 wherein said means for coupling said output signal to said selective valve means includes switching means operative in a first position to cause said valve means to allow fuel flow and in a second position to restrain flow. 
     
     
       3. The combination of apparatus according to claim 1 further including an additional heating source coupled to said evaporation chamber and operative to heat the same relatively independent of said exhaust gases. 
     
     
       4. The combination of apparatus according to claim 1 wherein said exhaust gas sensing means includes a photocell located in an exhaust gas conduit and means for illuminating said photocell through said exhaust gases to cause said cell to provide an output proportional to the pollutants contained in said exhaust gases. 
     
     
       5. The combination of apparatus according to claim 1 wherein said speed detecting means coupled to said engine provides a first control signal including a plurality of pulses at a frequency determined according to said speed. 
     
     
       6. The combination of apparatus according to claim 1 wherein said temperature sensing means and said exhaust gas sensing means include a monostable multivibrator having a trigger input coupled to said output of said speed detecting means. 
     
     
       7. The combination of apparatus according to claim 1 wherein said temperature sensing means includes means for disabling operation of the same during engine operation when the temperature of said heat chamber reaches a predetermined value, whereby said control of said selective means is accomplished primarily according to the output of said exhaust sensing means. 
     
     
       8. The combination according to claim 6 wherein the pulse duration of said monostable multivibrator associated with said exhaust sensing means is controlled by a field effect transistor.